Thermal and hydrodynamic performance of high humidity gas convection-condensation in a tube with edgefold-twisted-tape inserts was investigated experimentally

in which the main experimental parameters are wall temperature

vapor content

velocity and inlet temperature of the mixture.It is found that decreasing wall temperature and increasing vapor content enhance both convection and condensation

especially for vapor condensation.Structure parameters

such as the twist ratio and clearance between tube and tape

may change the condition of condensation film in the tube.The results show that higher twist ratio leads to higher swirl flow intensity and thicker condensation film

which decrease the heat transfer and increase the pressure drop.When the clearance between tube and tape is small

the condensation film may remain at the tip of tape and prevent the gas flowing through.When the clearance is large

the gas can flow through the tip of tape easily and the thickness of condensation film is small

so that the heat transfer is intensified.